Or-1, an orphan receptor belonging to the nuclear receptor family

ABSTRACT

This invention provides an isolated receptor having the amino acid sequence of FIG.  1  (SEQ ID NO:2) or substantially the same amino acid sequence as the amino acid sequence shown in FIG.  1  (SEQ ID NO:2) or an amino acid sequence functionally similar to that sequence, and DNA sequences encoding such a receptor.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to cellular nuclear receptors.

2. Brief Description of the Art

A large family of nuclear receptors has been identified which confercells with responsiveness to molecules such as retinoic acid, vitaminD3, steroid hormones and thyroid hormones. Extensive studies have shownthat the members of this superfamily of nuclear receptors activateand/or repress gene transcription through direct binding to discretecis-acting elements termed “hormone response elements” (HRE). It hasbeen shown that these HRE's comprise repeats of consensus palindromichexanucleotide DNA motifs. The specificity of the HRE's is determined bythe orientation of, and spacing between, halfsites (i.e. half apalindromic sequence)(Umenesono K., et al, 1991 Cell 65, 1255-1266).

Specific DNA binding is mediated by a distinct DNA binding domain,containing two zinc fingers, which is conserved among all thusdiscovered nuclear receptors. Three amino acids at the C-terminal baseof the first zinc finger (known as the “P-box”) are important for therecognition of the half site nucleotide sequence. Members of the nuclearreceptor superfamily have been classified into different groups on thebasis of the amino acid sequence within the P box.

Molecules thought to be nuclear receptors, as they are structurallyrelated to characterized receptors, but for which no ligand has beenidentified are termed “orphan receptors”. Many such orphan receptorshave been identified (see for example Evans R. M, (1988) Science240,889-895 and O'Malley, B. (1990) Mol. Endocrinol. 4 363-369).

BRIEF SUMMARY OF THE INVENTION

According to one aspect of the invention there is provided a novelnuclear receptor, hereinafter termed “OR-1”, having the amino acidsequence of FIG. 1 (SEQ ID NO:2) or substantially the same amino acidsequence as the amino acid sequence shown in FIG. 1 (SEQ ID NO:2) or anamino acid sequence functionally similar to that sequence.

An amino acid sequence which is more than about 90%, preferably morethan 95%, identical with the sequence shown in FIG. 1 (SEQ ID NO:2) issubstantially the same amino acid sequence for the purposes of thepresent application.

According to another aspect of the invention there is provided a DNAsequence encoding a nuclear receptor according to the first aspect ofthe invention. Preferably, the DNA sequence is that given in FIG. 2 (SEQID NO:1) or is a DNA sequence encoding a protein or polypeptide havingthe functionality of OR-1.

The nuclear receptor of the invention has a similar P-box configurationto the retinoic acid receptor (RAR), the vitamin D receptor (VDR), andthe thyroid hormone receptor (TR) and can be placed in the samesubfamily as those receptors.

Preferably, the receptor heterodimerizes with RXR to form a complex.

Preferably, the receptor interacts with RXR and binds to a DNA sequencecomprising at least one repeat of the DNA sequence -AGGTCA- (SEQ IDNO:10). Preferably the sequence is AGTCAGGTCACTCGAGGTCAGTCA (SEQ IDNO:11).

Preferably, the receptor modulates 9-cis retinoic acid signalling.

BRIEF DESCRIPTION OF THE DRAWINGS

The nuclear receptor of the invention, OR-1, and its method ofproduction will now be described, by way of example only, with referenceto the accompanying drawings FIGS. 1-5, in which:

FIG. 1 shows the amino acid sequence of a nuclear receptor of theinvention (SEQ ID NO:2);

FIGS. 2A and 2B show the DNA sequence of a nuclear receptor of theinvention (SEQ ID NO:1);

FIG. 3 gives a comparison between the primary amino acid sequences ofthe nuclear receptor of the invention and those of other members of thenuclear receptor superfamily;

FIG. 4 Localization of OR-1 mRNA—producing cells in rat tissues with insitu hybridization;

FIG. 5A gives the DNA sequences of seven potential HRE's DR-0-DR-6;

FIG. 5B illustrates the interaction between OR-1 or the retinoid Xreceptor (RXR) and the potential HRE's, DR-2 and DR4; and

FIG. 6 illustrates experiments showing that OR-1 confers 9-cis retinoicacid-responsiveness of RXR on a DR4-containing promoter.

DETAILED DESCRIPTION OF THE INVENTION

Cloning and Expression of OR-1

Rat OR-1 was cloned from a cDNA library from Sprague Dawley rat liver inthe commercially-available λZAP vector (Stratagene, USA) using thetechniques described in Göttlicher, M. et al (1992) Proc. Natl. Acad.Sci. USA 89, 4653-4657. Foetal and adult rat tissues were excised afterdecapitation and frozen on dry ice. Cryostat sections were hybridized to48-mer oligonucleotides complementary to OR-1 mRNA positions 100-151 and850-900 as described in Dagerlind, Å et al (1992) Histochemistry 9834-49.

Several unrelated oligonucleotides were also used as controls. Theaddition of 100 fold of the respective nonlabelled controloligonucleotide abolished all labelling observed with the OR-1 probes.

Plasmids

OR-1 cDNA was subcloned as an Eco RI fragment in pGEM-3Z (Promega) toproduce the plasmid pROR-1-Sp6, or in the multiple cloning site of pCMV5(described in Andersson, S. et al 1989 J. Biol. Chem., 264, 8222-8229)to produce the plasmid pCMV-OR-1. The reporter construct pDR4-AFcontains a SphI-XhoI fragment of the cDNA for a secreted form of humanPAP (placental alkaline phosphatase) described in (Berger, J. et al.1988 Gene 66,1-10) under the control of a DR4-TK-containing promoter,pRRXR-T7 and pCMV-RXR described previously in Gearing, K. L. et al 1993Proc. Natl. Acad. Sci. USA 90, 1440-1444.

DNA Binding Studies

Gel shifts were performed using in vitro-translated OR-1 and RXR withthe commercially-available TNT™-coupled reticulocyte lysate system(Promega, Madison USA). Proteins were incubated on ice for 15 min with 4μg of poly (dI-dC) and with unlabelled competitor DNA where indicated ina solution comprising 100 mM KCl; 10 mM Hepes, pH 7.6; 1 mMdithiothreitol; 1 mM EDTA; 10% (wt./vol) glycerol, before addition of0.5 ng of a ³²P-end labelled oligonucleotide probe. The reactionmixtures were incubated for a further 10 min at 22° C. beforeelectrophoresis at 200V and 4° C. in pre-run 4% polyacryliamide/0.25 TBE(0.089 m tris-borate pH 8.3, 0.025 EDTA) gels.

The following oligonucleotides and their complements were used asprobes:

DR0 AGCTTCAGGTCAAGGTCAGGTTCA (SEQ ID NO:3)

DR1 AGCTTCAGGTCACAGGTCAGTTCA (SEQ ID NO:4)

DR2 AGCTTAGGTCACCAGGTCAGTTCA (SEQ ID NO:5)

DR3 AGTCCAGGTCACTCAGGTCAGTCA (SEQ ID NO:6)

DR4 AGTCAGGTCACTCGAGGTCAGTCA (SEQ ID NO:7)

DR5 AGTCAGGTCACTCGTAGGTCAGTCA (SEQ ID NO:8)

DR6 AGTCAGGTCACTCGTTAGGTCAGTCA (SEQ ID NO:9)

Cells and Transfection

Embryonal carcinoma P19 EC cells were cultured in Dulbecco's modifiedEagle's medium supplemented with 10% foetal calf serum, nonessentialamino acids, penicillin (100 units/ml) and streptomycin (100 mg/ml).Chinese Hamster Ovary (CHO) cells were cultured in Ham's F-12 mediumsupplemented with 10% foetal calf serum, penicillin (100 units/ml) andstreptomycin (100 mg/ml). Cells were plated in duplicate in 35 mm Petridishes and transfected at 30% confluency, using lipofectin reagent(Bethesada Research Laboratories, USA) according to the recommendationsof the supplier. After 12 hours the medium was changed and supplementedor not supplemented as the case may be with 100 nM 9-cis retinoic acid(a gift of Hoffman-LaRoche) as indicated, and incubated for anadditional 36 h. Cell culture supernatants were then heated to 65° C.for 30 min. PAP activity was determined as the increase in A₄₀₅ at 30°C. in a 1 ml reaction mixture containing 0.75 ml of supernatant, 200 nMTris (pH 8.8.), 275 mM NaCl, 0.5 mM MgCl₂, and 5 mMp-nitrophenylphosphate. Transfections were repeated 6 times withdifferent plasmid preparations and data from a representative experimentis presented here.

Results

The OR-1 clone spans 1940 bp including a 55 bp long poly-A tail andcontains an open reading frame starting with an ATG corresponding to aprotein of 446 amino acids with a predicted molecular weight of 50 kD.The complete amino acid and nucleotide sequences of OR-1 are given inFIGS. 1 and 2A and 2B (SEQ ID NO:2 and SEQ ID NO:1) respectively. OR-1shows no striking homology to known members of the nuclear receptorssuperfamily: the highest homologies represent less than 10% in theN-terminal domain, about 50% in the DNA binding domain, and between20-30% in the putative ligand binding domain as shown in FIG. 3. Theamino-terminal domain of OR-1 (underlined in FIG. 1 (SEQ ID NO:2)) is 77amino acids long and to a large extent comprises a so-called “PEST”sequence, meaning that it is an amino acid sequence rich in proline,glutamic acid, serine, threonine, and aspartic acid residues. The DNAbinding domain consists of 68 amino acids including the nine invariablecysteines characteristic of the members of the nuclear receptorsuperfamily, as well as other amino acids that are found to be conservedin all members of this protein family.

Genomic Cloning

A rat genomic fragment has been isolated, that spans the DNA bindingdomain or OR1 and all the exons downstream of it. Most nuclear receptorsfor which the genomic structure has been determined have the two zinc“fingers” of the DNA binding domain encoded on separate exons. We haveshown that the whole DNA-binding domain is encoded by one exon in OR1.We have furthermore shown that this is also the case with RLD-1 (Mol.Endocrinol. infra), a closely related receptor “knock-out” mice of OR1and RLD-1.

Tissue Distribution of OR-1

To analyse the tissue distribution of OR-1 transcripts, in situhybridizations were performed on foetal and adult rat tissues. Labellingfor OR-1 was found in several tissues of both foetal and adult rats. Asdiscussed, below, prominent expression was observed in liver, lung,thymus, brown fat, salivary gland, thyroid gland, pituitary gland andretina whereas moderate levels were seen in developing cerebrum andcerebellum, in perichondrium around developing bones, heart and skin.Low levels of OR-1 mRNA was present in skeletal muscle as shown in FIG.4. In adult rats, strong labelling was found in lymph node, prostate,adrenal cortex and the intermediate lobe of the pituitary gland.Moderate levels were seen in liver, testis, salivary gland, thyroid andparathyroid gland, adrenal medulla, anterior pituitary and kidney. Inthe brain, a moderate signal was observed in neurons in the granularcell layer of the cerebellum and hippocampus.

1) Immune System

Prominent expression of OR-1 mRNA was seen in the cortex of the thymuswith lower levels in the medulla. In dipped sections grains were seenover most of the thymocytes in the cortex. Significant expression wasalso seen in the lymph nodes, whereas low levels were observed inspleen. Some cells in the bone marrow expressed OR-1 mRNA.

2) Endocrine System

Significant expression of OR-1 was seen in the anterior and intermediatelobes of the pituitary. In dipped sections grains could be seen overmost of the cells in the intermediate lobe and over the majority of thecells in the anterior lobe. The posterior lobe appeared virtuallynonlabelled. Prominent expression of OR-1 was detected in theparathyroid glands where most of the cells expressed OR-1 mRNA. In thethyroid gland moderate expression was observed and OR-1 mRNA washeterogenously distributed in different cell types. Most of theparafollicular cells expressed OR-1, whereas only part of the follicularcells were labelled. High expression in the adrenal gland was observedin all layers of the cortex, whereas lower levels were seen in themedulla. Expression of OR-1 was slightly higher in the zona glomerulosathan in the rest of the cortex. In the adrenal medulla the labelling washeterogenous and part of the chromaffin cells and ganglion cellsexpressed OR-1. In pineal gland some cells contained OR-1 mRNA.

3) Reproductive System

OR-1 could be detected both in male and female genital organs. In thetestis OR-1 mRNA was present in all cross-sections of the seminiferoustubules. The labelling localizes to the basal compartment of theseminiferous epithelium and grains could be seen mainly over primaryspermatocytes, whereas spermatogonia and germ cells at laterdevelopmental stages were non-labelled. The Sertoli cells and Leydigcells did not express OR-1 mRNA. A strong signal for OR-1 was evident inthe epithelium of the prostate gland and also in the epididymis, whereaslow levels were seen in the epithelium of the vesicula seminalis. In theovary oocytes at different stages of development expressed OR-1 mRNAwhile other cells appeared non-labelled. In the uterus the epitheliumwas strongly labelled and lower levels of OR-1 mRNA were seen in themyometrium.

4) Urinary System

Moderate expression of OR-1 could be detected in the outer medulla ofthe kidney, whereas in the cortex and inner medulla the labelling wasvery low or nondetectable. In dipped sections grains were seen overdifferent parts of the loop of Henle. The glomeruli, proximal and distalconvoluted tubules and collecting tubules did not express OR-1 atdetectable levels. The transitional epithelium of the renal pelvisexpressed OR-1.

5) Digestive System

In salivary glands the secretory acini and the ducts expressed moderatelevels of OR-1 mRNA. In the liver OR-1 mRNA was evenly distributedthroughout the liver and most, if not all, hepatocytes were labelled. Inthe intestinal tract OR-1 was expressed in the epithelium of stomach andsmall and large intestine.

6) Nervous System

Significant expression of OR-1 was seen in the sympathetic and sensoryganglia. In superior cervical ganglion most of the sympatetic neuronsexpressed OR-1 at high level and also the satellite cells were labelled.In dorsal root ganglion the labelling was heterogenous and variedbetween individual neurons. The Schwan cells of peripheral nervesexpressed OR-1 whereas oligodendrocytes in optic nerve were nonlabelled.In the retina the bipolar cells expressed OR-1. In the central nervoussystem OR-1 mRNA was seen in several areas including hippocampus andcerebellum.

7) Respiratory System

Moderate expression of OR-1 was seen in the bronchial epithelium and inthe alveoli.

8) Other Tissues

Low or non-detectable levels of OR-1 were seen in sketal muscle andheart. Also in white adipose tissue OR-1 expression was below thedetection limit. In skin a clear signal was observed in keratinocytes inthe basal part of the epidermis. A strong signal was seen inperichondrium around the cartilage in trachea. Low expression of OR-1could be seen in intra and extraorbital lacrimal glands.

The expression of OR-1 thus appears to be ubiquitous, suggesting thatthis receptor might have a house keeping function and/or mediate manyeffects by regulating the transcriptor of various genes. The tissuedistribution or OR-1 is different from the tissue distribution of RLD-1(Mol Endocrinol 9, 72-85, 1995) suggesting that these two isoforms mighthave different functions. OR-1 is particularly well expressed in tissuesinvolved in the immue system. It has been described that 9-cis retinoicacid plays a role in thymocyte development, being a potent negativeregulator of activation-induced T-cell apoptosis. Since OR-1 dimerizeswith RXR and is expressed at a high level in the thymus during the fetalstages, it may play a role in regulating T-cells development. OR-1 isalso well expressed in peripheral endocrine glands, in male and femalegenital organs and in the nervous system. The tissue distribution ofOR-1 is thus different from that of RXRα which has been described to benoticeably abundant in visceral tissues such as liver, kidney, lung,brain, heart, intestine and testis. We previously suggested that OR-1could act as a helper of RXRα in mediating the effects of 9-cis retinoicacid. Nevertheless we do not know whether OR-1 could also act as amonomer, as a homodimer or as a heterodimer with another protein thanRXRα. For example, it is possible that OR-1 modulates the actions ofRXRβ that shows a diffuse and probably ubiouitous expression, and ofRXRγ which has a more specific distribution.

OR-1 Interacts with RXR on a DR4 Motif in Vitro

A set of potential HRE's, DR0-DR6, having the DNA sequences describedabove predicted by the 3-4-5 rule (Umensono et al supra) was synthesizedand assayed in gel shift experiments using in vitro translated OR-1alone or in combination with RXR also translated in vitro. In vitrotranslation of OR-1 produced a protein of the predicted size of 50 kD.In the gel shift assays, OR-1 was unable to bind to any of the potentialHRE's but OR-1 combined with RXR, recognized the potential HRE DR4 whichis usually described as the thyroid hormone response element(TRE)(Umensono et al supra).

FIG. 5B shows that although OR-1 or RXR alone was not able to bind toDR4, together these proteins were able to form a specific complex withthis DNA element. The appearance of this complex depends on the presenceof RXR and is inhibited by a 10-fold excess of the specific DNA targetelement, but not by a 100-fold excess of an unrelated DNA element—seeFIG. 5B, lane 7)

OR-1 Confers 9-Cis Retinoic Acid Responsiveness or RXR on aDR4-Containing Promoter

Since OR-1 and RXR formed a specific complex on the DR4 sequence invitro, coexpression of OR-1 in embryonal carcinoma (EC) cells thatexpress endogenous RXR was tested to determine whether it could affectthe activity of a reporter gene under the control of a DR4-containingpromoter. RXR has been shown to be an auxiliary receptor for severalclasses of hormone receptors, controlling the ligand responses ofreceptors that form heterodimers with RXR (Yu, V. C. et al 1991 Cell 67,251-1266 and Bugge, T. H. et al 1992 EMBO J. 11, 1409-1418). Inaddition, it has been shown that 9-cis retinoic acid leads to effectiveRXR homodimer formation and that these homodimers bind and activateseveral retinoic acid response elements (“RARE's”), but not naturalthyroid hormone response elements (Zhang, X. K. et al 1992 Nature(London)358, 587-591). As previously described by others (Hallenbeck, P.L. et al 1993, J. Biol Chem.268, 3825-3828) our transfection studiesshowed no induction by 9-cis retinoic acid of RXR on a reportercontaining DR4 (FIG. 5). Expression of OR-1 allowed activation of RXR by9-cis retinoic acid on a DR4-containing promoter. In CHO cells that donot express endogenous RXR at as high a level as EC cells,cotransfection of RXR together with OR-1 is necessary to obtaininduction by 9-cis retinoic acid. Thus acting as a helper of RXR, OR-1appears to confer 9-cis retinoic acid signalling on DR4-containingpromoters.

11 1934 base pairs nucleic acid double linear cDNA not provided 1CAAGTGCTGT GGAGGAGCAA TCACCGGTGC GGACACAGAG CTCCCGCCTC CCACAGCCAT 60TTCCAGGGTA ACGAAGTAGG AGACCCCCTC CTGCGACCCC CTCACGATCG CCGGTGCAGT 120CATGAGCCCC GCCTCCCCCT GGTGCACGGA GAGGGGCGGG GCCTGGAACG AGGCTGCTTC 180GTGACCCACT ATGTCTTCCC CCACAAGTTC TCTGGACACT CCCTTGCCTG GGAATGGTTC 240TCCCCAGCCC AGTACCTCCT CCACTTCACC CACTATTAAG GAGGAGGGAC AGGAGACTGA 300TCCACCTCCA GGCTCTGAAG GGTCCAGCTC TGCCTACATC GTGGTCATCT TAGAGCCAGA 360GGATGAACCT GAGCGCAAGC GGAAGAAGGG TCCGGCCCCG AAGATGCTGG GCCATGAGCT 420GTGCCGCGTG TGCGGGGACA AGGCCTCGGG CTTCCACTAC AATGTGCTCA GTTGTGAAGG 480CTGCAAAGGC TTCTTCCGGC GTAGCGTGGT CCATGGTGGG GCCGGGCGCT ATGCCTGTCG 540GGGCAGCGGA ACCTGCCAGA TGGATGCCTT CATGCGGCGC AAGTGCCAGC TCTGCAGACT 600GCGCAAGTGC AAGGAGGCTG GCATGCGGGA GCAGTGCGTG CTTTCTGAGG AGCAGATTCG 660GAAGAAAAAG ATTCAGAAGC AGCAACAGCA GCAGCCACCG CCCCCGACTG AGCCAGCATC 720CGGTAGCTCA GCCCGGCCTG CAGCCTCCCC TGGCACTTCG GAAGCAAGTA GCCAGGGCTC 780CGGGGAAGGA GAGGGCATCC AGCTGACAGC GGCTCAGGAG CTGATGATCC AACAGTTAGT 840TGCCGCGCAG CTGCAGTGCA ACAAGCGATC TTTCTCCGAC CAGCCTAAAG TCACGCCCTG 900GCCCTTGGGT GCAGACCCTC AGTCCCGAGA CGCTCGTCAG CAACGCTTTG CCCACTTCAC 960TGAGCTAGCC ATCATCTCAG TCCAGGAGAT CGTGGACTTC GCCAAGCAGG TGCCAGGGTT 1020CCTGCAGCTG GGCCGGGAGG ACCAGATCGC CCTCCTGAAG GCATCCACCA TCGAGATCAT 1080GTTGCTAGAG ACAGCCAGAC GCTACAACCA CGAGACAGAG TGCATCACGT TCCTGAAGGA 1140CTTCACCTAC AGCAAGGACG ACTTCCACCG TGCAGGCTTG CAGGTGGAGT TCATCAATCC 1200CATCTTTGAG TTCTCTCGGG CTATGCGTCG GCTGGGCCTA GACGATGCAG AGTATGCCTT 1260GCTCATTGCC ATCAACATCT TCTCAGCGGA CCGGCCTAAT GTGCAGGAGC CCAGCCGTGT 1320GGAGGCTCTG CAGCAGCCCT ATGTGGAGGC CCTCCTCTCC TACACGAGGA TCAAGCGGCC 1380GCAGGACCAG CTGCGCTTCC CACGAATGCT CATGAAGCTG GTGAGCCTGC GCACCCTCAG 1440CTCCGTGCAC TCGGAGCAGG TTTTCGCATT GCGTCTCCAG GACAAGAAGC TGCCGCCTTT 1500GCTGTCCGAG ATCTGGGATG TGCATGAGTA GGGGCCGCCA CAAGTGCCCC AGCCTTGGTG 1560GTGTCTACTT GCAGATGGAC GCTTCCTTTG CCTTTCCTGG GGTGGGAGGA CACTGTCACA 1620GCCCAGTCCC CTGGGCTCGG GCTGAGCGAG TGGCAGTTGG CACTAGAAGG TCCCACCCCA 1680CCCGCTGAGT CTTCCAGGAG TGGTGAGGGT CACAGGCCCT AGCCTCTGAT CTTTACCAGC 1740TGCCCTTCCT CCCGAGCTTA CACCTCAGCC TACCACACCA TGCACCTTGA GTGGAGAGAG 1800GTTAGGGCAG GTGGCTCCCC ACAGTTGGGA GACCACAGGC CCCCTCTTCT GCCCCTTTTA 1860TTTAATAAAA AAATAAAATA AAAAAAAAAA AAAAAAAAAA AAAAAAAAAA AAAAAAAAAA 1920AAAAAAAAAA AAAA 1934 446 amino acids amino acid single linear proteinnot provided 2 Met Ser Ser Pro Thr Ser Ser Leu Asp Thr Pro Leu Pro GlyAsn Gly 1 5 10 15 Ser Pro Gln Pro Ser Thr Ser Ser Thr Ser Pro Thr IleLys Glu Glu 20 25 30 Gly Gln Glu Thr Asp Pro Pro Pro Gly Ser Glu Gly SerSer Ser Ala 35 40 45 Tyr Ile Val Val Ile Leu Glu Pro Glu Asp Glu Pro GluArg Lys Arg 50 55 60 Lys Lys Gly Pro Ala Pro Lys Met Leu Gly His Glu LeuCys Arg Val 65 70 75 80 Cys Gly Asp Lys Ala Ser Gly Phe His Tyr Asn ValLeu Ser Cys Glu 85 90 95 Gly Cys Lys Gly Phe Phe Arg Arg Ser Val Val HisGly Gly Ala Gly 100 105 110 Arg Tyr Ala Cys Arg Gly Ser Gly Thr Cys GlnMet Asp Ala Phe Met 115 120 125 Arg Arg Lys Cys Gln Leu Cys Arg Leu ArgLys Cys Lys Glu Ala Gly 130 135 140 Met Arg Glu Gln Cys Val Leu Ser GluGlu Gln Ile Arg Lys Lys Lys 145 150 155 160 Ile Gln Lys Gln Gln Gln GlnGln Pro Pro Pro Pro Thr Glu Pro Ala 165 170 175 Ser Gly Ser Ser Ala ArgPro Ala Ala Ser Pro Gly Thr Ser Glu Ala 180 185 190 Ser Ser Gln Gly SerGly Glu Gly Glu Gly Ile Gln Leu Thr Ala Ala 195 200 205 Gln Glu Leu MetIle Gln Gln Leu Val Ala Ala Gln Leu Gln Cys Asn 210 215 220 Lys Arg SerPhe Ser Asp Gln Pro Lys Val Thr Pro Trp Pro Leu Gly 225 230 235 240 AlaAsp Pro Gln Ser Arg Asp Ala Arg Gln Gln Arg Phe Ala His Phe 245 250 255Thr Glu Leu Ala Ile Ile Ser Val Gln Glu Ile Val Asp Phe Ala Lys 260 265270 Gln Val Pro Gly Phe Leu Gln Leu Gly Arg Glu Asp Gln Ile Ala Leu 275280 285 Leu Lys Ala Ser Thr Ile Glu Ile Met Leu Leu Glu Thr Ala Arg Arg290 295 300 Tyr Asn His Glu Thr Glu Cys Ile Thr Phe Leu Lys Asp Phe ThrTyr 305 310 315 320 Ser Lys Asp Asp Phe His Arg Ala Gly Leu Gln Val GluPhe Ile Asn 325 330 335 Pro Ile Phe Glu Phe Ser Arg Ala Met Arg Arg LeuGly Leu Asp Asp 340 345 350 Ala Glu Tyr Ala Leu Leu Ile Ala Ile Asn IlePhe Ser Ala Asp Arg 355 360 365 Pro Asn Val Gln Glu Pro Ser Arg Val GluAla Leu Gln Gln Pro Tyr 370 375 380 Val Glu Ala Leu Leu Ser Tyr Thr ArgIle Lys Arg Pro Gln Asp Gln 385 390 395 400 Leu Arg Phe Pro Arg Met LeuMet Lys Leu Val Ser Leu Arg Thr Leu 405 410 415 Ser Ser Val His Ser GluGln Val Phe Ala Leu Arg Leu Gln Asp Lys 420 425 430 Lys Leu Pro Pro LeuLeu Ser Glu Ile Trp Asp Val His Glu 435 440 445 24 base pairs nucleicacid single linear cDNA not provided 3 AGCTTCAGGT CAAGGTCAGG TTCA 24 24base pairs nucleic acid single linear cDNA not provided 4 AGCTTCAGGTCACAGGTCAG TTCA 24 24 base pairs nucleic acid single linear cDNA notprovided 5 AGCTTAGGTC ACCAGGTCAG TTCA 24 24 base pairs nucleic acidsingle linear cDNA not provided 6 AGTCCAGGTC ACTCAGGTCA GTCA 24 24 basepairs nucleic acid single linear cDNA not provided 7 AGTCAGGTCACTCGAGGTCA GTCA 24 25 base pairs nucleic acid single linear cDNA toscRNA not provided 8 AGTCAGGTCA CTCGTAGGTC AGTCA 25 26 base pairsnucleic acid single linear cDNA not provided 9 AGTCAGGTCA CTCGTTAGGTCAGTCA 26 6 base pairs nucleic acid double linear cDNA not provided 10AGGTCA 6 24 base pairs nucleic acid double linear cDNA not provided 11AGTCAGGTCA CTCGAGGTCA GTCA 24

What is claimed is:
 1. An isolated nuclear receptor, comprising apolypeptide consisting of the amino acid sequence of SEQ ID NO:2.
 2. Acomplex comprising the receptor of claim 1 and RXR.
 3. An isolatednuclear receptor, comprising a polypeptide consisting of the amino acidsequence of SEQ ID NO:2, wherein said receptor binds to a DNA sequencecomprising at least one repeat of the sequence AGGTCA (SEQ ID NO:10). 4.An isolated nuclear receptor, comprising a polypeptide consisting of theamino acid sequence of SEQ ID NO:2, wherein said receptor binds to a DNAsequence comprising the sequence AGTCAGGTCACTCGAGGTCAGTCA (SEQ IDNO:11).
 5. An isolated polypeptide consisting of the amino acid sequenceof SEQ ID NO:2.
 6. An isolated nucleic acid which codes for apolypeptide consisting of the amino acid sequence of SEQ ID NO:2.
 7. Theisolated nucleic acid of claim 6, wherein said isolated nucleic acidconsists of the nucleic acid sequence of SEQ ID NO:1.